text:
Legend for SkyVector's Sectional Chart outside the US
Does anyone know where can I find the legend for the symbols used by SkyVector's Sectional Chart for places outside the US? The US symbols are well documented but other places (e.g. the United Kingdom charts) seem to use a different set of symbols and line strokes for airspace classes.

IMO Skyvector is not very good for VFR outside of the US. It is clear their chart design is made specifically to match US airspace structure. When applied in other countries with different ways of doing airspace, they show a lot of stuff that is not relevant, and also miss some really important stuff. My point is, I don't think there is a separate legend, because they seem to (try to) apply the exact same style everywhere, even if it is not appropriate

If you’re after decent VFR eCharts then you could do worse than SkyDemon Light.  Plot your route and altitude and it’ll tell you all the airspace you’re bonging.

Europe adheres to ICAO conventions (Europe played a major role in ICAO creation), e.g. the 1/500,000 ICAO maps. The related legend in En and Fr. VFR chart snapshot of Paris area.

Thank you all for the replies. @mins The ICAO map you linked clearly show the different airspaces, unlike SkyVector -- that has cleared it up a lot. I wonder why SkyVector even bothers offering maps outside the US when the aeronautical information is so unclear, particularly in relation to airspaces.

@gilbertohasnofb, I suppose for IFR it is usable(ish) (though I can't tell how accurate their IFR layers are; but they are getting updated).

Aeronautical agencies in Europe countries, not limited to European Union, and now Eurocontrol adhere to ICAO conventions more strictly than the US, this is historical as some European countries played a major role in ICAO creation.
Differences between FAA and ICAO approaches translate into the wording and the documentation. In accordance with Chicago Convention, these differences are listed in the country AIP, at section GEN 1.7 (examples: UK AIP, US AIP).
ICAO is an organization to facilitate international traffic, not domestic traffic, therefore it mostly deals with IFR matters, but there is some guidance for VFR too.
Sectional
The 1/500,000 VFR map is recommended and its characteristics are described in Annex 4 of the Chicago Convention, at chapter 17. The legend is described in appendix 2. The chart shown below, and its legend are compliant with Annex 4.
About annex 4, the US AIP tells us: "Charts vary in their conformance to ICAO Standards" This explains why US Sectional charts at SkyVector are different from charts covering Europe.
ICAO compliant maps are usually not public domain. In France maps are produced and published by a semi-administrative agency, the Institut Géographique National (IGN), in collaboration with the Service d'Information Aéronautique (SIA) in charge of the local AIP. They are commercial products, SkyVector cannot directly reuse them, but they can reuse public basic aeronautical information and open map bases.
In contrast, the French administration, probably by an effect of its infinite generosity, makes 1/500.000 ICAO VFR maps public via the GIS site used for various topographic/land information and aerial views.
ICAO and SkyVector versions of the same area (around Bordeaux).

ICAO 1/500.000 VFR map, France SW area
SkyVector shows a version which is significantly simplified (source: SkyVector):

SkyVector sectional map, same area
A notable difference is prohibited and dangerous areas drawn in red for the ICAO flavor. SkyVector lacks indications for activities like parachuting, and frequencies for ATC within controlled areas.
The map base is also a bit simplified, the Gironde estuary is missing though it's the continent largest (surrounded by famous vineyards, used to ferry parts by Airbus, Dassault or Ariane Espace, and also one of the places where surfers can ride a tidal bore).
The ICAO legend (a fragment showing airspace depiction, the full legend is here):

ICAO VFR map legend
VAC: VFR approach charts
If addition of 1/500.000 maps, detailed VAC are publicly accessible in the AIP for visual approach, E.g. the visual approach for Mérignac:

VAC Mérignac
Enroute
IFR enroute charts, the counterpart of Sectional and ICAO VFR charts are publicly available in the AIP, at section 2.


text:
Do flight attendants do pinch-hitter training?
I was watching a Captain Joe video (Can a PASSENGER land a PLANE?) and he mentioned that he left out the 20 minutes it took the person to even figure out how to communicate with ATC. It seems to me that with a little training, a crew member would be much more prepared to handle such a circumstance.
Even if it's just one pilot, I could see the benefit of having a crew member able to share the workload (communications, checklists, etc).
I was wondering if there are any airlines that provide pinch-hitter type training to flight attendants (even if it's just a classroom course) in case one or both of the pilots are incapacitated?

I flew for two commuter airlines and two 747 carriers. At none of them was this done nor was it ever contemplated to the best of my knowledge.

Side comment: There are flight attendants who prepare for an airline pilot certificate, and some who are private pilots with IFR rating.

This is generally not standard practice. For one pilot training is particularly costly (even just in small planes) and would simply not be worth it to the airline, which is why there are two flight capable people in the cockpit to begin with.
Historically speaking there is evidence to the fact that it would not alter the outcome of the scenario. The closest instance of this occurring was possibly Helios Airways Flight 522 which lost cabin pressure at altitude incapacitating the crew and most aboard. Flight attendant Andreas Prodromou who held a UK Commercial Pilot License (but was not trained on the B737) was able to remain conscious via a portable air pack and make his way to the cockpit and into the captains seat. However he was un-able to take positive (meaningful) control of the aircraft due to lack of experience investigators eventually concluded after the crash.
There have been some successful talk down landings of substantially smaller aircraft.
FWIW, most modern airliners are sophisticated enough and have the controls concentrated enough that they can be flown single handedly in a manageable fashion.

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text:
Does the TIS-B "hockey-puck" contain VFR mode-C targets with unconfirmed altitude?
When receiving TIS-B traffic via ADS-B In, I'm curious what mode-C targets are included.
Is it only mode-C traffic with confirmed altitude in contact with ATC services (presumably with a transponder code)?
Or does it include traffic with unconfirmed altitude that's probably squawking 1200? Does it leave off altitude in that case? How would it know if traffic is within +/- 3,500' of your aicraft to give you your "hockey-puck" of traffic?

The AIM covers most of the operations and limitations of TIS-B on page 4-5-18

TIS−B is the broadcast of ATC derived traffic information to ADS−B
  equipped (1090ES or UAT) aircraft from ground radio stations. The
  source of this traffic information is derived from ground−based air
  traffic surveillance sensors. TIS−B service will be available
  throughout the NAS where there are both adequate surveillance coverage
  from ground sensors and adequate broadcast coverage from ADS−B ground
  radio stations. The quality level of traffic information provided by
  TIS−B is dependent upon the number and type of ground sensors
  available as TIS−B sources and the timeliness of the reported data.
  (See FIG 4−5−8 and FIG 4−5−9.)

According to the AIM all transponder equipped (A/C/S) aircraft are included

Only transponder−equipped targets (i.e., Mode A/C or Mode S transponders) are transmitted through the ATC ground system
  architecture. Current radar siting may result in limited radar
  surveillance coverage at lower 10/12/17 AIM Surveillance Systems
  4−5−19 altitudes near some airports, with subsequently limited TIS−B
  service volume coverage. If there is no radar coverage in a given
  area, then there will be no TIS−B coverage in that area.

section d. TIS-B Limitations offers some more info
The system is not perfect and unconfirmed altitudes may display as shadows

(b) The ADS−B−to−radar association process within the ground system
  may at times have difficulty correlating an ADS−B report with
  corresponding radar returns from the same aircraft. When this happens
  the pilot may see duplicate traffic symbols (i.e., “TIS−B shadows”) on
  the cockpit display.

More on transponder requirements

(d) The TIS−B system only uplinks data pertaining to
  transponder−equipped aircraft. Aircraft without a transponder will not
  be displayed as TIS−B traffic.

So pilot A in his Cherokee with a mode S transponder will show up but pilot B in his cub with no electronics and only a hand held who may be on radar will not show up.
This technical order covers the topic important phrase

TIS-B is the ADS-B In function that provides for the in-cockpit
  display of other aircraft (without ADS-B) in the vicinity that are
  being seen via FAA secondary radar. General observations can be made
  during the flight to verify that known radar targets are appearing in
  the correct relative position on the ADS-B display(s) in the flight
  inspection aircraft. Of course, if there are no such
  targets-of-opportunity in the area during the flight, the opportunity
  to check TIS-B in this way will not be possible.

So if you are coming up on secondary radar you will be included in the ADS-B/TIS-B broadcast. ATC receives 1200 codes with altitude (encoder provided) so they will show up, and in my recent experience flying in the northeast most VFR traffic does show up. Aircraft with no transponder will not show up (radar target only). Im not sure what happens in the case of no altitude reporting.

@StephenS i believe i have added a bit which directly answers the question. If they are transmitting and being received on SSR they are showing up.

It's hard to prove a negative, but showing them consistently not saying something when they could may be the best evidence available in this case.

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text:
P-51, P-82; how about a P-113 or beyond?
The P-82 improved on the P-51 in range
and slightly in top speed, at the expense of cruise speed and service ceiling.
This was helped by lengthening the fuselages for more fuel tanks, and by changing the engine and propeller.
How might a triple (or quadruple?) Mustang like the imaginary one pictured behave aerodynamically?
Which laws of diminishing returns would apply?
Ignore its operational role and weaponry.
(Were any manned triple fuselage airplanes ever built, not just proposed?)

I would guess that the drag increase would be non-linear, and would cross the "good idea threshold" pretty quickly...

The Rutan Voyager has three fuselages.

Wasn't the Voyager notoriously unstable in flight?  Not saying that's specifically due to the fuselages, just that the Voyager isn't exactly a good place to look if you want to see the Good Idea Threshold, because it was designed to meet one very specific and extreme goal which was, arguably, not a Good Idea.

Two aircraft spring to mind powered by four Merlins, the Avro Lancaster and the Handley Page Halifax. What does that tell you about the likely handling of a aircraft with four heavy piston engines?

Voyager is usually described as twin-boom, like the P-38.

At some point it's just becoming silly.

But what kind of silly?  Exactly how and when does it cross the good idea threshold?

A P-113, huh? Really? P-113?

Fighters are great, but it may be time to look into bombers, cargo transports, or airliners if you like long range multiengine aircraft.
However, the load distribution has merit in your design.
One might just put fuel tanks and engines out on the wings, with a larger central fuselage that has space for a bathroom (critical in long flights).
This one, and the 707 can cruise much faster and higher, and this one had greater range.

So is the question's answer then "like a B-36 or B-47 or 707"?

@CamilleGoudeseune i did consider an elongated nacelle behind the engines for fuel rather than underslung tanks.  The design is possible aerodynamicly but is impractical.

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text:
Why do cathay pilots forget their flight number?
I hear so many times over frequency "cathay.. uh.. xxx" and always wonder if they have some kind of reason why pilots cant seem to memorize it.

Commercial pilots rarely fly the same flight number twice in a row, they may be on flight 010, then 218, then 037. Commercial airplanes have a place to put the flight number in the cockpit so the pilots can read it, sometimes a pilot will start to transmit and realize they can't remember the callsign and they have to look at the piece of paper, which is why they pause.
The same is true with GA airplanes, I belong to a flying club with 10 different planes, each with a different registration, and I may fly any one of them on a given day. The registration is generally placarded on the dashboard, I have more than once started a call and had to refer to it.

yes sir I understand, I fly for airlines also, and we use a memory aid on the yoke where we can set the flight number. It's pretty conveniently located so you can see it easily, which is also why im wondering

Nobody knows for sure @Dededkd, there's many competing scientific theories on memory. My personal view is that when Aviating, Navigating and Communicating in a complex and challenging environment callsign is a low priority for mental processing.

It is a abstract number with little or less meaning to some existing memory, while a city as destination should have already some mapping in the brain to existing information.


text:
What is the difference between APV I and APV II?
Been reading all these ICAO documents about APV I and II and none of them clearly describe (from a pilots perspective) the difference. Please help


text:
How to compare two SFCs, one in thrust, the other in power (both turbofans)?
I want to compare some recent turbofan engines in terms of fuel efficiency, particularly the PW535A and FJ44-4.
I found the SFC for the PW535A to be 0.44 lb/h/lbf. I couldn't find anything on the FJ44-4, except for an earlier model. The FJ44-3A has a SFC of 0.456 measured in kg/kW*h.
Firstly, how can I effectively compare these? I tried rearranging the units so they could immediately be compared but kept ending up with laughably different values.
Furthermore, where might I be able to find data on the FJ44-4?

The most important information that is missing from your data is the speed at which both values were measured. Thrust ($T$) and power ($P$) are connected by speed ($v$):$$P = T\cdot v$$

I think your reference for the FJ44-3A contains a typo for units, and the 0.456 is actually in lb/h/lbf. It is in a table comparing piston, turboprop and turbofan aircraft and was likely just copied over into the third table. Kg/Kwh is common measure for shaft output and an aberration for a fan output.

For comparing turboprops vs turbofans, you would normally divide the turboprop's SFC by the prop's thrust coefficient at comparison airspeed.
For two turbofans, always compare TSFC. It's a function of airspeed and altitude too, but the curves can be found in the paperwork, and for common engines online.
Jet engine SFC is rarely mentioned and has few practical applications outside of engine design and engineering. All the customer (pilot, etc) will see is thrust.
The FJ-44's TSFC is right there on the wiki page you've linked. The entry for 44-4 is n/a, but you can generally assume it about the same among the variants. The actual vatiance is within a couple percent.

Both engines are turbofans

The FJ44-3A figure specifies engine power. The PW353A specifies thrust, so it includes the propeller. The propeller isn't 100% efficient, so that's the factor you're missing.

Both engines are turbofans.


text:
Can a private pilot legally act as a safety pilot for an instrument student performing approaches under the hood?
Someone is looking for a safety pilot so that they can build instrument hours under the hood and practice instrument holds / approaches. Is there any reg that would prevent me (a private pilot) from acting as a safety pilot during this flight?
Would I need to hold an instrument rating for us to legally perform instrument procedure practice? We are both only private pilots, but the other pilot is receiving instrument training.

The safety pilot must possess a private pilot certificate with category and class ratings appropriate to the aircraft being flown 91.109(c)(1)(i)

(c) No person may operate a civil aircraft in simulated instrument flight unless -

The other control seat is occupied by a safety pilot who possesses at least:
i. A private pilot certificate with category and class ratings appropriate to the aircraft being flown; or
ii. For purposes of providing training for a solo cross-country endorsement under § 61.93 of this chapter, a flight instructor certificate with an appropriate sport pilot rating and meets the requirements of § 61.412 of this chapter.

That's the only requirement.


text:
What are the fundamental differences between a parachute and a paraglider?
I want to know the difference between a paraglider and a parachute. Can you explain the difference between a paraglider and a parachute in general?

By 'hole' do you mean the cell openings on the leading edge of the canopy?  https://en.wikipedia.org/wiki/Paragliding#Wing

@MichaelHall: On the other hand, modern ram-air parachutes have more in common with paragliders than with the traditional "military" round/cruciform parachute.

By "parachute" do you mean an old-style round parachute with a vent hole on the top, or a square ram-air parachute with ram-air holes along the leading edge?

A paraglider is an inflatable wing pressurized by the dynamic pressure at its leading edge openings, that makes lift and glides like any other wing, whereas a parachute with a hole in the center is strictly a drag device designed to operate at a 90 degree angle of attack and doesn't produce lift.
The hole is there to allow air trapped by the down velocity of the canopy to vent out the top instead of spilling out the sides.  This reduces its tendency to swing. Putting vent holes at one location at the edge of the canopy generates a slight forward thrust that introduces a bit of glide, and pulling down the center with additional center suspension lines reduces the frontal profile and improves glide further.
The Paracommander was the ultimate circular canopy and used additional directional venting at the top, with a pulled down center to reduce the frontal profile.  Those canopies are a little bit wing-like and have a better glide ratio than conventional round parachutes, maybe 1.2 to 1 (I used to jump one in the mid 70s).
Ram air parachutes are basically paragliders that operate with much higher wing loadings, fewer cells, and lower aspect ratios, with higher minimum speeds, with heavier lines and fabrics to tolerate opening shock at terminal velocity.
With modern zero porosity fabrics, ram air parachutes achieve glide ratios of up to 3:1, whereas paragliders are made with many smaller cells (to make the wing thinner), thinner lines, lighter zero porosity fabric, and have lower wing loadings with higher aspect ratios.  That achieve glide ratios of around 6 to 10 to 1.

The first paraglider flights were carried out on Ram air ‘square’ parachutes, and paragliders were then developed to have better flight characteristics.  A parachute needs to have extremely reliable deployment, good stability in the air and a survivable descent rate, while a paraglider needs a good glide ratio, good airspeed and needs to be easy to fly (fatigue!) for up to several hours at a time.  As a result, parachutes tend to have few cells, large cell openings and are made from strong but porous materials, while paragliders have many more cells, often more suspension lines, higher aspect ratio and are made from much less porous materials.  Since paragliders are normally inflated on the ground prior to launch, slow inflation isn’t a problem and line tangles can be dealt with easily.  In contrast, a parachute may be deployed with a very high airspeed where a line tangle is unacceptable and a non-porous paraglider would likely suffer serious damage.
In the early stages of paraglider development, aspect ratios were increased so much that when hit by a gust, the canopy would collapse from the center, like the closing of a book, resulting in several deadly accidents. Lower aspect ratios make the chute more robust against collapse.

Nice answer! Last sentence, did you mean to say a non-porus parachute (not paraglider), or even the parachutist using it, would suffer serious damage, presumably at opening shock?

@Ralph J I meant non-porous paraglider because that’s what they are but a parachute made of 80g non-porous nylon would fare no better.  And yes the parachutist would not have a pleasant experience.  In-air deployment using a paraglider is possible (d-bagging) but it typically done with the lowest possible airspeed and with the wing folded so that inflation is somewhat progressive.

Earlier ram air parachutes and paragliders were made of a low porosity ripstop nylon fabric, and the newest ones are made from zero porosity ripstop fabric for improved performance.  I used to own a ParaCommander round when I was jumping in the late 70s, and it was made of nylon taffeta fabric.


text:
Can foreign military flying hours be counted towards an EASA ATPL in Hungary?
I'm an ex- Indian Air Force helicopter pilot with about 4000 hours of flying experience, including some 2500 hours as captain and about 500 hours as an instructor.
Is there any means by which, I can get the flying I have done in the Indian Military, at least partially counted towards the requirement for obtaining an EASA ATPL licence. I am currently enrolled in a flying school in Hungary and they insist I fly the same syllabus as an ab-initio, as according to their Compliance Manager, no part of my flying experience can be added towards the requirement of Hungarian CAA for grant of ATPL.
I have tried to contact Hungarian CAA, but haven't received a response yet.
Would be grateful for suggestions/tips!


text:
14 CFR § 91.213 - Inoperative instruments and equipment. <Cessna 172S NAV III>
I am working on a commercial right now, but still, this confuses me a lot.
For example, during the preflight, I found that the airplane has inoperative equipment. And our operator has no MEL. Then I need to follow 91.213(d) since we do not have a MEL.

Check VFR-day type certificate
Check KOEL
Check AD's
Check 91.205

KOEL, 91.205 are pretty easy to understand.
But 1. VFR-day type certificate. I looked at TCDS a lot, but I cannot find any equipment list.
On the Comprehensive Equipment List (Section 6) R = Required items or equipment for FAA certification. Does it mean that the equipment listed on the CEL, and indicated with R, are considered as TCDS VFR-day type certificate?
Looking at this page

In summary:
The standby altimeter is marked as required in the Comprehensive Equipment List because it's an IFR certification requirement
Operationally, the standby altimeter is only required for IFR flight, per the KOEL

Basically, Pondlife wrote that

The Comprehensive Equipment List (section 6 in the POH) lists all the equipment required by the type certificate:

If the equipment is required by any operations (VFR-day, VFR-night, IFR-day, IFR-night), it should be required by CEL. However, the alternate static air source is required by KOEL (IFR operations) not required by CEL (S).

AD's. I know how to look them up on the FAA website. However, what if the check airman asked me to verify if it is not required by AD, how should I verify that the inoperative equipment is not required by AD?

Sorry for the language. I am an international student, not fluent in English. But I really appreciate your help.


text:
What's the difference between a Sole Means Navigation System and a Primary Means Navigation System?
For bonus points, how you define a supplemental means navigation system?

Can you give us some context? Are you asking about how they are defined by regulation? If so, for which country or regulator?

Sole means it is the only system, primary implies there is a secondary or even tertiary system, and supplemental means it supplements another system.

Thanks for the response. Just to clarify, a sole means system can function on it's own, while a primary means system requires other systems to aid it in order for it be a reliable means of navigation?

Not to be rude, but please look up the definitions of sole, primary, and supplemental, and then let us know if you have a specific difficulty relating them to the general subject of aviation.  Better yet, if there is an actual aircraft or navigation system description that you are trying to understand better, if you can quote it we might be able to clarify its performance limitations for you.


text:
How are performance classes for helicopters/rotorcraft defined?
In helicopter/rotocraft literature, such as ICAO Annex 14 Volume II (how to design heliports), there's constant references to performance classes. How can I tell what performance class a helicopter is in?
So far the only definition I have found is: in the event of engine failure, Performance Class 1 helicopters should be able to land within the rejected take-off distance available or continue safe flight, while Performance Class 3 will require forced landing. (https://www.casa.gov.au/standard-page/project-os-1124-incorporation-performance-class-concepts-australian-helicopter).
This is hard to apply to helicopters where I only have some basic specifications. Are there any other, easier to use, definitions for performance classes? I'm hoping for something like runway codes for aerodromes, which are derived from landing distances and wing spans of aircraft that use the runway.

Multi-engine helicopters have 3 Performance Classes defined at certification that is related to single engine performance and how this affects follow-on risks following an engine failure.
Class 1 helicopters have massive reserve power and can continue flight on one engine.  They have engines that are way larger than necessary for normal operation and normally operate at a fraction of their power potential until called upon to do it all.  Risks following engine failure are low.
Class 2 helicopters have somewhat less reserve power, and can continue flight temporarily on one engine, but not indefinitely.  Risk factors are higher.
Class 3 helicopters have little reserve power and are generally forced down when one engine fails, although at a much gentler descent rate than an autorotation. Risk factors are highest.
I was looking for a link that provides a good detailed description but haven't had much luck.


text:
What's the difference between fog, fog banks, and fog patches?
My meteorology textbook (from Pooley's Air Pilot's Manual series) has a list of abbreviations used in met reports and forecasts. They include:

FG for "fog"
BCFG for "fog patches"
PRFG for "fog banks"

What's the difference between these three?

@mins You might want to post that as an answer because it has all the info in it.

@mins Very descriptive link, thank you. Let me know whether you're going to write that up as an answer; if you don't want the rep, I will do it myself.

@DanHulme: I won't write a full answer, so feel free to compose yours. Thanks for asking :-)

Thanks to mins's link, the Australian Government Bureau of Meteorology explains everything in detail. To summarise the particular part I was asking about:

FG on its own means fog (visibility < 1000 m) covers more than half of the horizon
PRFG and BCFG are fog covering less than half of the horizon
PRFG (fog bank) is more extensive than BCFG (fog patches)

Another way of looking at it is like cloud cover descriptors. FG is like BKN or OVC: more than half the horizon is covered. PRFG is SCT, and then BCFG is FEW.
All the above are used when the temperature is above freezing point and the fog reaches more than 2 metres above ground. If the fog is only below 2 metres agl, it's shallow fog MIFG instead. If the temperature is below freezing, so the fog consists of supercooled water droplets, it's freezing fog FZFG.

Sounds like Eskimos and all their words for snow!

BCFG is patches of fog (BC = BanCs, French origin)
PRFG is partial fog, meaning that part of the aerodrome is covered in fog, but the coverage is  not extensive enough to qualify as fog (FG).
VCFG is fog in the vicinity of, but not on the airport
MIFG is shallow fog (MI = mince, French origin)
FZFG is freezing fog

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text:
Cessna 172: at which RPM should the oil pressure reach the green arc?
I am part of a team developing a Cessna 172 P model for FlightGear, an open source free flight simulator. We are now trying to improve the oil pressure and temperature simulation, and we have a question concerning the behaviour of the oil pressure at startup. The oil pressure gauge in the model P ranges from 0 PSI until 115 PSI, with a green arc region between 50 PSI and 85-90 PSI. What we are trying to figure out is in which circunstances the needle should be in the green arc region.
I have checked many different checklists for the 172 and many state that the throttle should be at 1000 RPM for the oil check, so that the oil pressure should be at least 50 PSI. On the other hand, the 1982's POH does not state that the oil check should happen at a particular RPM; it only says that the throttle should be OPEN 1/8 INCH on p. 4-7. But the POH is quite confusing concerning this issue, since it simply says Oil Pressure -- CHECK but not that the oil should be on the green arc. To add more confusion to it, on p. 4-12 it says:

After starting, if the oil gauge does not begin to show pressure
  within 30 seconds in the summertime and about twice that long in very
  cold weather, stop the engine and investigate.

So nothing again about the green arc or 50 PSI, just about the gauge being alive. This is perhaps the reason those checklists include the 1000 RPM figure, perhaps the engine is not able to give 50 PSI or more of oil pressure when at idle (aprox. 750 RPM in the case of our model).
TL;DR

in the Cessna 172P, at which RPM should the oil pressure be equal to or above 50 PSI?
what is the procedure for oil pressure check, should it be done at 1000 RPM or at idle throttle?

Your answer will be elusive.  The problem is that oil pressure is a function of the oil, oil temperature, time, engine pressurized oil draw (the "wear" of the engine), and RPM.
I am confident a model could be created using the above parameters, and possibly one or two more.  However, you are probably not interested.
I have about 8000 hours of instruction given in C172M, which is a different engine.  With 100 weight oil, at 20C or higher, I teach that oil must be moving up within 5 seconds, and with 1000 RPM it must be approaching or in the green within 10 seconds or there is an engine shutdown.
In contrast, with 80W oil, at 32F (we require preheat if engine temp is below 32F and the aircraft is at home base), I teach that the oil pressure must be moving within 5 seconds and in the green within 15 seconds.
These times are on our customized checklist, and do not address cold weather ops although they are quite common for us.
We will not start taxi until the oil is in the green arc. We always look for movement of the oil gauge within seconds after the engine start. We bring the engine above 500 RPM, but not necessarily to 1000 RPM waiting for the oil to rise up.  A factor in not going to 1000 RPM immediately is that the engine wear without full flow on a journal bearing is the square of the surface velocity. On the other hand, the pump volume is nearly linear with respect to the rotational velocity.
Also, note that we use straight weight oil 90% of the time.  Multivis oil will behave differently.
To address your two questions, I propose you use the following:
-1000 RPM for oil check all the time
500 RPM idle typically yields 30 to 35 PSI

I am confident a model could be created using the above parameters, and possibly one or two more. However, you are probably not interested. Actually the oil pressure in our project is modelled using all these parameters you mention, what I have been looking for is for real data to be used to calibrate the model in order to make it fly according to the POH. The main issue was the unclear wording in the POH and the different check procedures in several checklists (1000 RPM vs throttle 1/8 inch). And your answer has been very helpful with all that, many thanks.

In my (unofficial) experience, Oil Pressure moves slowly, and definitely depends on the engine needing to warm up.
So the early checklist is just to make sure that the Pressure is alive and increasing, and appears to be headed for the green-arc.  (If it isn't increasing, you are probably just about out of oil and need to shutdown immediately!)
Generally, I expect the pressure to be in the green arc by the time I'm in the run-up area, doing my runup checks at 1800 RPM. (Typically about 3-5 minutes after ignition).   When I throttle back from 1800 RPM to an idle of about 700-1000, the pressure drops to the bottom of the green area, maybe a bit under it.
All of that is unofficial, and my instructors never really hammered it home much more than the checklist says.

Mongo's answer is much better than mine; and I may adopt his view of checking Oil Pressure in more detail immediately on startup.

but rest assure that I really do appreciate your answer; in particular in such types of issues, different experiences are very useful for us.


text:
What does "cabin class" mean when describing GA aircraft?
Does it mean that there's a door with stairs? Or pressurized? Or that the seats are arranged a certain way?

Where did you see this?

“Cabin Class” is a very common term to describe larger general aviation aircraft. I don’t think there is an official definition. Most have 6-8 seats in a “club seating” arrangement. Most are pressurized with an air-stair door, but I don’t believe these items are required in order to be called “Cabin Class”.

I would say Cabin Class implies a bulkhead of some type separating the cockpit from the cabin, so that they are two separate compartments.

the classic definition is a plane whose fuselage is wide enough to allow access to the rearmost seats via a gap or aisle between the forward seats. It also allows the pilot to get into the cockpit through the same boarding door that the passengers use, by climbing in between the front seats and stepping over the middle console.


text:
How do you know when wind is tailwind or headwind based off of a figure or like looking at the weather?

So when I drawed the runways and then where the wind is comes from. And I still don’t know how to know if it’s tailwind or headwind. When I visualize it in my head the wind is coming right and is pushing the side of the airplane at all directions. How should I visualize it and what helps you understand if it’s head or tail wind?

Thank you

To reiterate what I mentioned in my answer: Your yellow line depicting the landing airplane is backwards. The yellow arrow shows the airplane landing to the East, so it would be using Runway 9. The question asks about an airplane landing to the West, so it would be using Runway 27.

Yea I have it landing, wait I thought runways are opposite so that is why I put the 27 on the left side. I'm confused.

Runways aren't "opposite." Runways are numbered according to what your compass indicates when you're pointed down the runway. Read my answer carefully.

The problem is you have the compass orientation backwards.  North is top, as the little black pointer shows, so runway 36 is landing toward the top of the image not the bottom, and runway 27 is landing toward the left of the image, not the right.
Once that is resolved, you are landing on 27 as per the question, so right to left, or to the west, and the sock shows the wind from the northwest, so right quartering headwind.

A tail wind is a wind blowing from the tail to the nose, a head wind is a wind blowing from the nose to the tail.

How do you know when wind is tailwind or headwind based off of a figure or like looking at the weather?

The wind moves the wind sock smaller end away, so this smaller end is equivalent to the arrow head on a figure.
Usually the wind is not aligned with the aircraft heading, it is neither a pure tailwind nor a pure headwind. It has both a tail or head wind component and a cross wind component. You need to break the wind vector into its two perpendicular components. On the figure below, if north is up, the aircraft heading is 90° and the wind is about 315°. (The wind sock would have its smaller end aligned with the blue arrow head.)

Now you have isolated the tail/head component, you can evaluate its direction and determine whether this component comes from the tail or from the nose.
Indeed one component can be null, e.g. if the wind is perpendicular to the aircraft heading, there is a cross wind component but no tail/head wind component. Actually that's the angle between the heading and the wind which can tell you quickly if there is a tail or head wind component:

If the wind blows from a direction which forms an angle smaller than 90° with the aircraft heading, then the wind has a head wind component.

If the wind blows from a direction which forms an angle larger than 90° with the aircraft heading, then the wind has a tail wind component.

This 90° angle limit determines four quarters, head-left, head-right, tail-left, tail-right for the direction the wind is blowing from. This notion of quarters is the one used in the picture you included in your question. E.g. if the heading is 270° and the wind is 315°, the angle from nose to wind direction is 45° on the right, this is a right-quartering head wind:

Note your heading and the wind direction are not using the same convention on your second picture. It looks like your wind is 315° and your heading is 90°, or your heading is 270° and your wind is 135°, depending on where north is.
The magnitude of the tail/head wind component is proportional to the wind magnitude and to the cosine of the angle. The cross wind magnitude, which depends on the wind magnitude and the sine, is also important as any aircraft has a cross wind limitation for taking off and landing.

A headwind means the wind is coming toward your head (the nose of the airplane). A tailwind means the wind is coming toward your tail (the tail of the airplane).
Runways are numbered: What would your compass say if you were pointed straight down the runway.
Wind direction is numbered: What would your compass say if you were angled so that the wind was a perfect headwind.
This makes it very easy. If the wind is "270 at 10" and you are on "runway 27" it is a perfect/direct headwind. If (like in your example) the wind is "300 at 10" and you are on "runway 27" it is a right quartering headwind.
If you think about it in terms of geometry/trigonometry, a perfect headwind is pointed straight toward you—0º offset from where your nose is pointed. As the wind shifts, the crosswind component goes up and the headwind component goes down. Eventually the wind is coming directly from your side—in other words, 90º offset from where your nose is pointed. This is a complete crosswind. As the wind continues to shift, the crosswind component goes down and the tailwind component goes up until eventually the wind is coming from right behind you—in other words, 180º offset from where your nose is pointed.

Wind is from, and runways are to a given direction.
Start by adding West, South, and East (you have North) to your diagram.
The red wind arrow is correct.  The windsock confirms wind from the northwest.
The yellow landing arrow is $backwards$, representing a landing on eastbound runway 9.  The pilot would have a left quartering tailwind.
Turn the landing around to a more sensible runway 27, and one has a right quartering headwind, landing to the West.

The opening of the wind sock is where the wind comes from. You are landing on runway 27 so you are heading toward 270 magnetic, from right to left in this diagram. So the wind is coming from the right and from ahead. Try draw everything on a flat sheet of paper to create look from above view.


text:
How to calculate the vertical profile for a LOC only approach?
I am kind of stuck for calculating a descent path on the ILS RWY 7 approach into KORL. Assuming the glide slope is not available and you have to use the localizer only, what is the best way to calculate the descent and Decision to Land Point?

As you can see in the approach chart, the MDA is 660 feet for the localizer only approach. Assuming a glide path of 3°, I calculated a descent of 318 feet per Nautical Mile. However, that would not correlate to the 1919 feet at the Outer Marker.
What would be the best way to calculate / plan the approach in this example?

The approach shows that the glideslope (if it were working) is a three degree descent angle.   You can calculate your own visual descent point (VDP), since one isn't provided for you, by taking the height above touchdown (600 ft. in this case) and dividing it by 300 ft/NM.  This gives you 2.0 miles from the runway.  Since the chart shows the runway threshold at 0.2 DME, your VDP will be at 2.2 DME.
Assuming that your navigation equipment does not provide a pseudo-glideslope, your best bet is to descend at your normal rate (in a light airplane I would say 800-900 fpm) until you level at 660 ft. (the MDA), then fly to your calculated VDP (2.2 DME) and if you have the required visual cues then descend to the runway knowing that it will be a standard 3 degree descent (300 ft./NM).  If you don't have it at this point, then you can start an early climb and fly the missed approach.

Put another way, first you calculate your VDP:
$$\frac{Height~Above~Touchdown}{Descent~Rate}=VDP~Distance~From~Runway$$
$$\frac{600ft}{300 ft/NM}=2.0NM$$
$$VDP=Runway~Threshold+VDP~Distance~From~Runway$$
$$0.2DME+2.0NM=2.2 DME$$
Then you fly the approach:

Cross HERNY at 2,000 ft.
Descend to minimums (660 ft.) at 800-900 fpm.
Fly to 2.2 DME at 660 ft.

At 2.2 DME, if you see the runway environment, start your descent and land
If you don't see the runway, start your climb and fly the published missed approach

I built a calculator to help with these types of calculations.
https://my.rockymountainflight.com/canpa
You can input the icao identifier for an airport. I pull up the current METAR for you. You input the altitude, altimeter setting, temperature, indicated/calibrated airspeed and wind velocity, degrees the wind is off from the runway heading, altitude to lose and the distance to lose it.

You have to first descent from 2000 to 1020 in 2.7 miles. With the current weather, you would have a 62 knot ground speed in a C172. Traveling 2.7 NM losing 980 feet is a 3.42 degree descent angle which requires a 375 fpm descent.
You could do a similar calculation from BUVAY to the VDP. 0.6 nm to lose 360 feet. That is a 5.64 degree descent angle and 620 fpm.


text:
How do I find the registration or serial number for the aircraft I flew on specific trips in the past?
I understand that there are various paid subscription services that allow me to search back up to a year in the past for the IDs of any flight and the histories of any aircraft.
Is there a free (or one-time fee) service or API for identifying the aircraft I've flown on specific dates and flights in the (up to several years) past?

I think FlightAware has historical data, but it is a subscription service.

@RonBeyer: Yes, that's what the question says.

You linked FlightRadar, I mentioned FlightAware, two different services...

@RonBeyer: "various" and "is there a free (or one-time fee)...".

It's a one-time fee if you cancel the subscription right away...

@RonBeyer: That's not really the question, is it.

Excuse me, Who is asking? :)

For specific dates and flights you might be able to get this question answered on a local aviation forum. At least in the Netherlands I know various examples of people who wanted more information about flights up to twenty years ago and got answered by people who had flight logs or other information for a specific day.


text:
Is there a list of what information different airlines track about their flights?
It has been suggested in the media and in some answers here that airlines vary in the information they track about the status of their flights. Is there a publicly available resource that lists what information different airlines have about the location and status of their flights? For example, could a British Airways flight over the Atlantic or the middle of the Pacific have "vanished" in the same way that the Malaysian flight over the Gulf of Thailand?

You'd really need to ask each airline to find out what they track - but this question about ACARS may be of interest to you as well

I don't think such a list exists, why would all airlines share that informations?

@DeltaLima: If it were mandated to do so.

The only thing you'll find in the regs are the requirement that an the operator be able to locate, track and communicate each airplane it operates, for FAA ops anyway.  See this A http://aviation.stackexchange.com/a/2158/258 for more details on that.

There is no particular list that provided by airlines company about their flights because it can be misused, but several statuses are provided:
(from http://www.flightstats.com/go/AirportTracker/airportTracker.do#1)

Geographic Coverage - FlightStats provides definitive information for approximately 99.5% of U.S. flights, and better than 86% of flights worldwide.
Completeness - FlightStats queries multiple sources to create a record for each flight enabling us to offer a broader range of information (for example, gate information).
Accuracy - We have invested heavily in the areas of parsing, interpretation and error checking and developed the logic that enables handling of difficult issues such as cancellations, diversions and changing schedules.
Codeshare Support - Our codeshare logic enables us to deliver flight information for both the operating and the marketing carriers, filling what is often a major gap in coverage.
Real-time data sources include:

FAA ASDI Data Feed
European Data Feed
GDS (Sabre, Amadeus, Apollo, Galileo)
Direct Airport / Airline Data Feeds

Batch data sources include:

Innovata Schedules
TSA Security Wait Times
Security Information
Health Information
Consular Information


text:
Can a private pilot receive recurring training while waiting for a special-issuance medical approval?
In the last year, I have had to undergo bypass surgery. I am fully recovered now (and past the mandatory 6-month waiting period), but have just been apprised by my AME that my 3rd class medical deferral is likely to take a month or two for the FAA to process.
I am also in a partnership, and our insurance requires annual recurring training. Normally, all four of us (partners) take the recurring training at the same time, and get a discounted rate as a result.
As fate would have it, this year's recurring training will fall into the time I am waiting to hear back from the FAA. Since the flight portion of the recurring training (essentially an IPC) is conducted under the supervision of a CFII, can I complete it without a current medical certificate?

Without knowing the nature of the recurring training this boils down to whether you need to be PIC during the flights. If the CFII can be PIC and you arent acting or logging PIC then you shouldnt need a medical.

My understanding is that your medical is currently invalid (because you had bypass surgery and need to get your medical reinstated), so you currently cannot exercise the privileges of your certificate - i.e. you can't act as pilot in command of a flight (or any other required crew member in a role for which a medical is required).
As Casey pointed out, you've got an out that allows you to still take training (and even to fly generally): Someone else with a valid medical and a certificate appropriate to the category & class of aircraft needs to act as the (legal, FAR 91.3) pilot in command while you're operating the controls.
If your CFII is willing to accept that role (and the attendant liability) while giving you your training you can go up with them and complete the recurrent training your insurance company requires, but this is something you need to discuss with your CFI prior to going up with them.

Not directly related to my answer, but it's worth noting that things get a little more murky in terms of logging PIC time - I'm not sure where that would fall from a regulatory standpoint. (You are rated for the aircraft which means as sole manipulator of the controls you would normally qualify for logging PIC time, but you don't have a current medical which means you can't technically act as PIC. My gut says you can't log PIC time in this situation (and to be legally-safe you definitely shouldn't) but I'm not sure what reg or counsel opinion to cite to back that gut feeling up up.)

As we discussed in chat, it is perfectly legal to log PIC time in this situation per 14 CFR 61.51(e)(i).


text:
Are all planes painted white first?
Is white used as base paint before other colors? So is the paint on coloured parts thicker than in white parts?

Not always.  This video (screenshot below) shows an ex-US-Airways A319 being redecorated in the American fashion.  While the blue and red paint for the tail detailing is indeed applied on top of a white undercoat, the blue and red paint for the detailing on the mid-to-forward fuselage is applied directly on top of the yellow primer coat, with no white undercoat; the coat of white paint on these parts of the fuselage goes on top of the other colors.

That said, some browsing through airliner-painting videos gives the impression that, although a white undercoat isn't universal, it does seem to be surprisingly common, even for liveries that otherwise have little or no white.


text:
Sensors used on a blade
How to measure the strain, temperature and rotational dynamics on a running engine fan blade? How can you do the experiment?

There are devices like strain gauges, temperature sensors, and accelerometers that are all quite small and can be attached to almost anything.  You will also need something to read those devices like a microcontroller, also quite small today.  You'll also need some way to power it, a small battery comes to mind.  I'd use a wireless connection of some sort as a wired connection to a rotating blade is tricky.

Welcome to stack, this video on the FlightChops channel touches on that issue briefly. They don't go much into detail because its likely considered proprietary methods for doing business competitively. https://www.youtube.com/watch?v=t5t6VefAyRo


text:
Can you take off from a country road in a ultralight aircraft?
Can I take off from a country road in a ultralight aircraft (In the USA). I have seen resources online saying yes and no. Does it vary from state to state?

Yes you can.  I have.  But actually this is meant as an editing suggestion.  Did you mean can you legally / in compliance with regulations?

As long as you aren't doing anything reckless or otherwise against regulations, the FAA doesn't care.
Your state or local regulations may prohibit it, though. For instance, it is illegal to do so from a public road in California.

While the FAA may not have any regulations about this, the state, county, municipality having jurisdiction over the road may not permit the operation of unlicensed motor vehicles.

@jwh20 Yes. How is that different than what I said in my second paragraph? Are you making a distinction that it may be illegal to use an ultralight on a public road even where it is legal to do so in a part 23 aircraft?


text:
Would I need a drone license if the drone is flown by ai and not a remote?
I heard of some AI flown UAV's and was wondering. if I made my own AI flown drone/plane would I need a drone license? (Assuming I would use it for commercial purposes and not just for fun).

A "remote" is the thing you control your television with, not your drone or model airplane.  (Although that usage is becoming annoyingly more common these days.)  Traditionally hobbyists call the thing you hold in your hands the "transmitter".  The FAA likes to call it the "ground station".  Ground control to major Tom...

If you think you can avoid doing the paperwork for a drone license by delegating the in-flight decisions to "AI", then you can be assured the FAA will take the complete opposite view. The amount of regulatory paperwork that would be required to fly a fully atonomous UAV would be enough to bury all but the most determined entrepreneurs. It may not even be possible (yet).

@WPNSGuy Sorry, AI may have been the wrong term, it would basically just be a program that would follow out a flight plan. It would not really be making its own decisions

In that case, you're still the pilot and still need a drone license.

Assuming USA, if it is above certain size points, you need varying levels of 'license'. Even if just for fun/hobby.
Commercial use always requires a license.
The relevant Commercial regulation is Part 107.
"If you have a small drone that is less than 55 pounds, you can fly for work or business by following the Part 107 guidelines. To fly under Part 107 rules, there are 3 main steps."
Finally, define "AI". The aircraft makes its own decisions about when and where to fly? Currently, that does not exist.

You can make a drone that autonomously chooses when and where to fly.  It will make bad decisions.

@AnonymousPhysicist - That is not "intelligence". Just a rng selecting waypoints, within a prespecified range.

Because nobody lets AI's run rampant - except for the nordic countries in season 3 of the BBC series Humans.
Every AI is under the responsibility of someone who caused it to be in that situation.  If you train your monkey to fly an airplane, and let the little guy fly solo, it's you who will be paying to replace the Reaper drone the monkey collides with.  Because you're the one who set that sequence of events into motion!
The best liability shield you could have is a corporation... but then that corporation better have sufficient cash on hand or insurance to cover its liabilities, or the courts will go after the stockholders.

"the courts will go after the stockholders." I thought the entire point of a corporation was that the stockholders are immune from liability beyond losing their stock if the company goes bankrupt, except under the rare circumstances that allow piercing the veil? If what you said is true, and creditors can seize the assets of stockholders of bankrupt corporations, then there's really no difference between a corporation and a sole proprietorship or limited partnership with a savings account set aside for liabilities.

@Someone if you control a corporation then direct that corporation do crimes, you have various liabilities the corporation does not magically shield you from. If you direct the corporation to do sensible/legal business things but it gets into trouble anyway, then normal bankruptcy protections probably apply. There are some interesting questions on liability for AI lead decisions within a business but this question is not really the place to hash them out.

@Someone Incorrect.  I mean what you say is correct, but you misquoted me out of context.  The rest of my sentence describes the "rare circumstances" that allow piercing the veil.  Speaking of context, every statement on StackExchange is by definition in the context of a question. We are talking about letting AIs run loose, remember. A person who wraps that in an LLC instead of carrying insurance, and expects that veil to hold, is deluded.


text:
Is it possible to calculate Calibrated Airspeed from True Airspeed, Temp, and Pressure Altitude?
Looking at a digital E6B, there is a function for calculating CAS that I am trying to recreate and program myself.

Inputs:

Pressure Altitude
Temp in Celcius
True Airspeed

Outputs:

CAS
Mach #
Density Altitude

I am 100% sure that you can go from CAS to TAS so in my mind that implies that you can go the other direction, I just have not been able to find the calculations so far. I am not a big math person or physics and AI has not helped either.
For the Mach #, I can successfully calculate that, and while I haven't got the Density Altitude yet, I feel more confident about figuring that one out.
So, does anyone know how one would use these 3 inputs (and probably some constants) to get the Calibrated Airspeed?

Yes, it did. I saw this before, but I did not have all the pieces of the puzzle so to speak but went over it again and found away to slightly modify that which worked and got me the expected result.

Airspeeds are usually calculated indicated >> calibrated >> true >> ground speed. Calibrated to true calc uses temp and pressure altitude. So I don't see any reason why if you have that information, you can't reverse the calculation if A = B + C then B = A - C.

This is a duplicate so I can't leave an answer, but the "excel formatted" version of this would be CAS = TAS * ( 1 - 6.8755856*10^-6 * DA )^2.12794 where DA = Density Altitude in feet.  This does not take compressibility into account so will only be accurate for light aircraft speeds (low Mach numbers).  Also, the constraint for most altimetry and airspeed functions is below the tropopause at 36,000 feet.  Also. remember that all temperature calculations are done by first converting to Kelvin, or you will get crazy answers.


text:
Where can I find dimensions of the Lockheed Model 14 Super Electra?
I'm doing a school project and I'm trying to find accurate dimensions of the aforementioned aircraft. Is there any website or database that has this information?

Wikipedia states the following:
Length: 44 ft 4 in (13.51 m)
Wingspan: 65 ft 6 in (19.96 m)
Height: 11 ft 5 in (3.48 m)
Since schools don't like Wikipedia, I guess I'll have to find another source to confirm the dimensions.
Edit: "The Encyclopedia of Military Aircraft" gives the following dimensions for the Ki-56:
Length: 48 ft 11 in (14.9 m)
Wingspan: 65 ft 6 in (19.96 m)
Height: 11 ft 10 in (3.6 m)
Since the Ki-56 was a copy of the Lockheed 14 Super Electra with a 1.5m stretch, subtracting 1.5 from 14.9 gives 13.4m, which is pretty much the same as what Wikipedia states for the Super Electra.


text:
Is ATPL a universal license?
What I mean by ‘Universal’ is to be used anywhere.
is this the case or do pilots flying between America and the UK just have both CAA and FAA ATPLs?

Annex 1 of the International Civil Aviation Organization (ICAO) creates mimimum standards for crew licensing that all ICAO member nations recognize. The ICAO is an agency of the United Nations, and was established by the Chicago Convention on International Civil Aviation in 1947. So far, every UN member with the exception of Lichtenstein and the Holy See (no airports) have ratified the Chicago Convention and are members of the ICAO.
So yes, an FAA ATP license is recognized by treaty in nearly every UN member state.

Sadly this is not the case. The ICAO annexes provide recommended standards that countries can choose to adopt or lodge a "difference" to, and just continue to do their own thing. In practice, most (if not all) countries require you to go through a conversion process before flying an aircraft registered to that country. For example I can't just use my Australian licence to start flying for United, I'd have to convert it to a US certificate to fly an N registered aircraft in the States, and vice versa. However, a Lichtenstein licence is ineligible for conversion, as they are not recognized.


text:
What jobs are available outside airliners in England, and how do I get into them?
I’m currently under training and intend to take on aviation as a lifelong career, but I’ve never taken to the idea of airliners.
What general aviation jobs (like survey, aerobatics, cargo, small charters) are seen to be in demand in England? In my job searches i’ve only really ever come across F/O placements…
Any advice would be greatly appreciated.

instructor, test pilot, calibration pilot, skydiver pilot


text:
Where do I go to enter into my first Air Show?
Where/Who do I go to in order to enter for participation in my first Air Show in the UK?
I’m sure this isn’t an easy thing to do but my initial searches haven’t been much help…

The first place I'd start is British Aerobatics who are located at a lovely little airfield called Fowlmere just to the west of historic Duxford. They're a really helpful bunch, I have flown with them a couple of times. I'm sure they will be able to put you in touch with the right people to get involved in airshows.
They also have a a page on Entering competitions which you might find useful.


text:
Helicopter hammerhead-like maneuver
A response to a previous question indicated, “In a helicopter, aft cyclic (“pitching up” in a plane) will only serve to make the helicopter climb and slow down until it reaches equilibrium in the new attitude.” I understand that is not the same thing as a “retreating blade stall.” My question is: what will happen if you pull aft cyclic until the helicopter is vertical to the ground, that is, pointing straight up to the sky and you hold that attitude and power setting? Will it simply “slide” backwards vertically when it can climb no further (like a hammerhead stall in a fixed wing)? How do you recover?

If you pull a helicopter into a vertical attitude, you'll have to unload the rotor to maintain the vertical path, since the rotor's down thrust is also part of your forward thrust component, unlike an airplane with a separate propeller than can continue pulling the plane up while the wings are unloaded.
You can't maintain a vertical climb on rotor thrust like you would an airplane, because the rotor thrust component acting on the helicopter's vertical axis will pull the machine sideways, toward the rotor. You have to effectively become a ballistic object with the rotor disc more or less a pinwheel doing nothing at that point, and the height of the hammerhead would be limited to the inertial energy in the machine once vertical.
Once vertical, when it stops going up, you would kick the thing around with the tail rotor to get it pointed down and accelerate down and pull out.
Of course, you'd better be in a helicopter with a semi-rigid rotor system that is designed to tolerate aerobatic maneuvers and 0-G flight without danger of exceeding blade flapping limits and chopping the tail boom off.
If you were in a machine with a 2 blade teetering rotor, forget about it; you'd become a falling object from mast bumping breaking off the rotor head as soon as you got zero G.

Thank you! I understand; that makes sense.


text:
Plane Identification (Coast Guard, Air Force base region)
I live in Clearwater Florida and multiple times a day, I have giant multi-prop Coast Guard planes, ans choppers flying low over my home.
However, today as I sat outside, I heard one but it sounded a bit different.
When I looked up, I expected to see the White with red Coast Guard "Super Hercules" flying low over us ... but the plane I seen was different.
First off, it's elevation was lower than average.
But the big difference was color. It appeared a dark gray with what looked like a red symbol on its side and tail. (Almost like a circular shape of letters painted over each other in one single spot.)
It had 4 props, and I usually get a picture of things like this, but I was shocked... I thought "Maybe a special Coast Guard plane took off out of Clearwater base?" Then I thought "Ahhhh... must be an Air Force Plane from MacDill... ?" However, they rarely send up large planes west of the base at such a low altitude.
So, I spent too much time wishing I snapped a picture as I went down a rabbit hole searching the web for answers. So now I'm here. Lol
TL;DR Dark grey/black 4 prop (like a Coast Guard Super Herc) plane with a single red symbol on its side and tail flying low , due west, as if it launched from Clearwater Coast Guard base. It definitely wasn't the usual white CG or grey AF plane color
Thanks again in advance.

High wing or low wing? conventional tail? Please tell us more about the physical characteristics.

AC130's are dark gray, but I couldn't find a red marking on any of the images I saw online. There's a unit based in Crestview, FL.

@PeterKämpf it was a low wing. I wonder if it was a private plane. It looked nearly identical to the big Coast Guard Planes... I was just like "???" Like if you go to drink an iced tea, but it's root beer .. but for the eyes. I was just kinda shocked

@RetiredATC yeah, it was a darker grey, and smaller than an AC130. I wonder if it was a private plane, or one from a movie set or something. It seemed almost comical, like my eyes were playing tricks on me.

"almost comical" is a strange way to describe a plane. Did it look like a P-3 Orion maybe?


text:
Canadian Approach Plates: Why does the minima show that DME is required but the procedure name does not?
I see so many plates that contain lines of minima requiring the use of DME, but the title does not indicate DME is required. For example, the "LOC RWY 27" approach into CYYJ. The title indicates that DME is not an additional navigation requirement, however the line of minima (only one in this case) says the opposite (LOC/DME, meaning DME is required). Why is it not then titled "LOC/DME RWY 27"? The CAP GEN says that any additional navigation requirements are indicated within the minima lines of the approach, so if there is only one minima line requiring the use of certain equipment, why is it not in the title?

For the US, the title now only includes navigation equipment for the lateral guidance of the final approach course. As an example, a previously named ILS or LOC/DME is now just ILS or LOC. Did the Canadians adopt a similar practice? I would suspect that is the case but I cannot find anything definitively.

@Timbo I bet we did...we massively overhauled our plates a few years ago, I imagine we adopted this as well. Thank you for the insight, this makes a lot of sense. I'm going to go through more plates and see if I can find any examples that would either prove/disprove this.

Most likely from amendments over time. Here is the current version of this approach:

and an older version:

As you can see, the older version has circling minima in addition to the LOC/DME minima. From a literal reading, circling to land does not require DME, thus why this is not called LOC/DME RWY 27.
However, there doesn't seem to be any way to identify the FAF or the MAP without DME. I can think of a couple possibilities here:

The plate has had errors in all its forms.
On some previous form of the plate, there was some other method to identify the FAF and MAP. Perhaps outer and middle markers? Thus, at some point, this approach could be flown without DME, and the name has stuck.

@757toga A literal reading of older plate indicates that circling to land doesn't require DME. I'm not sure how one is meant to identify the FAF without DME, though. Radar? RNAV?

@757toga It's definitely possible this is just a mistake, and it always should have been called LOC/DME.

@Chris-RegenerateResponse thank you for including the older plate. That the name carried over makes sense.


text:
What does MALSR stands for in an IFR chart?
I was going through PPL Jeppesen (I am a student pilot), and I was wondering if you could help me out by telling me the meaning of this. Been looking in different websites and other literature, but I just can’t find an answer.
Thank you very much for your patience and help

"I just can’t find an answer." Did you try Google?  The answer comes right up as soon as you put in MALSR

https://flightlight.com/products/medium-intensity-approach-lighting-system-runway-alignment-indicator-lights-malsr/#:~:text=MALSR%20(Medium%20Intensity%20Approach%20Lighting,the%20centerline%20of%20the%20runway.

I’m voting to close this question because No Effort Whatsoever.

Going to give you a tip for your future flight training. For questions relating to aeronautical publications and general flight stuff, go ask your flight instructor first. Usually your flight instructor will have the answer for you or be able to point you in the right direction to find that answer.

Where can I find detailed information about ground lighting systems exist in aviation?


text:
Would military aircraft jam TV signals?
Various military aircraft just flew overhead on their way to the Trooping of the Colour in London.
At the same time, my Television's signal went completely dead, and then restored once they had gone. (It's a table top arial, but usually manages to get a decent signal.)
Is this a coincidence, or would they be jamming similar frequencies?
They were several helicopters, and according to what I can find, they were:
Juno HT1 - x3
Wildcat HMA2 & Merlin HM2 - x2
Wildcat AH1 & Apache - x4
Wildcat AH1 & Merlin Mk4 - x2
Chinook x3 & Puma HC2

I remember as a kid in the late 1960s/early 1970s that any time any helicopter flew over our house, the TV would become a staticky mess.   This was true for all helicopters, including civilian.  As tuner electronics improved in quality in the early 80s, it seemed to subside and not happen any more.  From the early 80s on my TVs were always cable fed, so it never happened to me again.

I grew up in London in the 1960 with analog black and white TV on VHF and a rooftop antenna. When planes went over the picture could 'flutter' due to reflections from the aircraft metal fuselage and wings rapidly adding to and subtracting from the signal and the TV set automatic gain control being unable to keep up. Later on UHF this got better. With digital over-the-air TV you wouldn't get this fading - the way a modern set works you either get a perfect picture or nothing. A TV with a marginal set top antenna could be OK most of the time and just give up when the signal got degraded.

As previously commented, a reflection of the signal by the aircraft is likely to be the cause. Even though DVB-T is designed against echo by using a guard interval between symbols, it has a limit. You would know if you're close to the limit by looking at the BER, bit error ratio. Any value larger than $\small 2 \times 10^{-4}$ indicates little margin for degradation.

It’s unlikely that they would be deliberately jamming TV signals - what’s the benefit apart from drawing additional attention to their presence?  All types of radio receivers, including TV, are to some degree sensitive to out-of-band signals, so any sufficiently powerful transmitter using a different frequency band could cause problems, depending on how good your receiver is at rejecting unwanted noise.  A ‘bunny ears’ antenna on top of a TV set is likely to be quite vulnerable.  Military aircraft will be using radar, transponders, airband radio and so on, so there’s a good chance that one of those could cause interference.

I accept that there's little military benefit in stopping people from watching TV; I thought perhaps that those frequencies might have a role in something else. But consequential interference through other frequencies may well be sufficient, as you point out. Thanks!

@benwiggy There is little military benefit in stopping friendlies from watching TV during peacetime...

@T.J.L. True., which is why I though it might be incidental. Mind you, friendly civilian populations have endured worse for no strategic gain....

The electronic warfare transmitters, jammers, are seldom turn on during routine flights. While I know little about such facilities in the UK, in the USA there are several ranges designed to test the equipment with transmitters for them to jam.
Even when performing maintenance tests, we had to be careful as certain civilian systems could potentially be affected, especially if the transmitters were not exactly on frequency or had bandwidth issues.
If blocking them was needed for some reason, some aircraft certainly do carry equipment that could have interfered with broadcast TV signals.


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How to Define Aerodynamic Center for Real-World Airforil?
When using thin airfoil theory, there exist a point that the moment about this point does not vary with Cl, which is the aerodynamic center.
However for most of the real-world airfoils, Cm does vary with Cl, and Cm is measured relative to AC, which contradicts with the definition of aerodynamic center that moment is constant. So how is AC defined in the first place for a real-world airfoil?

As you also said, the definition of aerodynamic center comes from the thin airfoil theory so it's not 100% valid for "real" airfoils. Data for $C_m$ is always plotted in respect to the quarter chord point by convention. Don't know if this answer your question

@sophit if that comment was intended to be an answer, please make it so.

@CGCampbell: not sure this is what the OP asked, let's see what and if the OP says

@sophit that is exactly what I wanted. Thank you for the answer!

Perfect  Then I'll convert it an answer

@sophit so clicking that checkmark means the answer is accepted right? New to this platform and can’t be sure

Yes thanks! You can also upvote it if you like.

@sophit I did, but not enough reputation to cast a vote unfortunately

As you also said, the definition of aerodynamic center comes from the thin-airfoil theory so it's not 100% valid for "real" airfoils.
Data for $C_m$ is anyway always plotted in respect to the quarter chord point by convention, which is the theoretical aerodynamic center from the thin-airfoil theory at subsonic speeds.


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Help identifying small low-flying aircraft over western US?
Have spotted this aircraft flying over the western U.S. more than once this July: a couple of times in early July north of Spokane, WA, and today over the Silicon Valley area. All times it was flying very low, but was relatively quiet for how close to the ground it was. It appears to have two propellers on each wing and is a plain gray, which makes me think it may be military. My searches for military aircraft that fit this description have come up blank though. Any help with identification is appreciated!
Blurry photo below is the best I was able to get.

First time I've ever heard a C-130 described as quiet!  Usually their distinctively loud sound is one of the main give-aways!  Maybe that's somehow unique to when the pass over at higher altitude-- you get that all-pervasive gently throbbing roar-- PS re "First time I've ever heard a C-130 described as quiet!"-- or small!!

That's why I initially dismissed considering it a C-130: it seemed too quiet and too small, even though the shape looked similar!

@quietflyer I expect from their description of it as "small" that it was in fact higher up than OP thought it was.

Well, it wasn't a toy (radio-controlled, perhaps electric) model of a C-130 was it?  Perhaps in "giant scale" so that it looked like a real a/c?  (Just kidding-- mostly!)  PS @Chris-RegenerateResponse -- yes just as w/ birds, size of flying a/c can be deceptively hard to judge of altitude is not known, and vice versa, unless the thing in question has already been definitively identified--

Probably will conclude that I misjudged the altitude, thanks for the help everybody!

You may wish to edit your title - that is a HUGE aircraft!!!

The odds that you saw the same aircraft in both locations are extremely remote. You probably saw multiple instances of the same type.

I believe this is an HC-130J Combat King II based on the wing tanks and paint scheme, from the 129th Rescue Wing, which is based out of  Moffett Federal Airfield, California, based on where you reported seeing it (the Silicon Valley).
https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104468/hc-130j-combat-king-ii/
https://www.dvidshub.net/feature/hc130jfeaturepage

I wouldn't put too much stock into a paint scheme, and the wing tanks can be fitted to any (all?) variants, used for transport/ferrying, and more.


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Engine performance under best economy vs best power mixtures and how it relates to TAS on a fixed pitch propeller?
I am currently training on a very basic PA-28-161 (it has a single reciprocating air-cooled engine with fixed pitch propeller). I have a rather involved question on mixture as it relates to power as it relates to TAS, and have searched extensively for insight on both this website and others yet have struggled to find an explanation. My suspicion is that a POH issue/error has been the issue, but I would like an expert opinion. I hope my detailed thoughts and subsequent discussion help others with the same problem. For this question I will reference performance charts from the below POH link:
https://www.aerovalley.org/wp-content/uploads/2019/07/Warrior-II-Manual761780.pdf
First, two priors I had going into this (and if these are wrong, then perhaps we can cut this discussion short):

For a fixed pitch propeller, given a density altitude, the RPM is a monotonic function of the engine power output, since this is the only way the engine can "express" itself to the outside world. Using the POH's example from pg. 98 (titled Engine Performance; page number is expressed as that of the pdf document), given a 5000 ft pressure altitude and 15 C OAT, a 2625 RPM is associated with 75% power. A lower power output at the same altitude will always show up as a lower RPM and vice versa. Additionally, these RPM values as they relate to the proportion of power output are fixed, i.e. pg. 98 is an immutable property of the airplane. As an aside, the max power the engine is rated for may not be achievable at higher altitude (this is not a turbocharged engine after all): this makes sense and indeed, the "iso-power lines" slope up and to the right on pg. 98.
Given an altitude and fixed pitch propeller RPM (presuming steady-state level flight is possible at the combination provided), there is only one airspeed that can possibly be obtained (everything here assumes there is no wind).

Now, notice on pg. 98 there is a box that compares gallons per hour fuel flow for a best power or best economy mixture at each level of power, 55%, 65%, or 75%. This is where I'm getting at my issue, namely that we can have different levels of fuel flow for a specific level of power...but a specific level of power (given an altitude) is associated with a specific RPM...which should be associated with a specific airspeed. Different fuel flows resulting in the same airspeed would intuitively be odd.
The POH examples demonstrate my confusion: looking at pg. 101 (Best Power Cruise Performance), we are operating at 75% power, which using the same environmental assumptions as before implies an RPM of 2625...and this is associated with a TAS of 122.5 kts. Now jumping to pg. 102 (Best Economy Cruise Performance), we are again operating at 75% power, but because the fuel mixture is optimized for efficiency the airplane flies at just a TAS of 118 kts. This is the issue: what does "operating at 75% power" mean on pg. 102, namely for Best Economy mixture assumptions? Because if my priors are correct, that 75% power should be associated with a specific RPM which should yield a specific airspeed...yet the airspeed on best economy is lower.
One way I have come up with to reconcile all this is that engine performance (and specifically the mapping of RPM to % power) has to account for the mixture setting (and so my first prior must be amended to include mixture setting). So in reality, pg. 98 Engine Performance looks totally different if re-done with a Best Economy mixture at every point (but the POH has only included the Best Power version). I would assume that RPM under a Best Economy mixture would be shifted lower in each case of 55%, 65% , or 75% power settings. Or more succinctly, the maximum power (and therefore RPM) one can achieve is higher when providing the engine with a best power mixture vs a best economy mixure...so the whole mapping shifts. In other words, this is a three dimensional relationship of RPM (or TAS) = f(g(% power, mixture), altitude). I suppose in that case that pg. 102 has a typo and it should read "Cruise Power: 75% best economy mixture" rather than best power mixture.
Is this the right way to think of this? Has all my trouble been due to a lack of exhaustive (no pun intended) engine performance charts and a POH typo? Is the right way of thinking about my theoretical Best Economy Engine Performance chart as a leftwards shift of the Best Mixture chart?

I agree that these charts seem to disagree with each other on the surface. "75% best economy mixture" doesn't make much sense either since you're forbidden from operating above 75% power at a lean mixture.

Yes I've read the same re: operating above 75% on a lean mixture. But couldn't you still have a theoretical max power achievable on a leaned mixture with which to cut new 55, 65, and 75% baselines for a separate best economy mixture engine performance chart? I agree, the POH clearly does not want you doing that seeing as pg. 102 stops at 75%, but is it fair to think of a separate engine performance charts for both best power and best economy mixtures, each with a different max baseline? That would make significantly more sense to me!

No doubt there is such a power, but I'm not sure why a pilot would care what that power is. Honestly I wouldn't worry about it much- it's not like the plane has a "powermeter" so it doesn't really make a difference to the pilot if they're running at 73% or 75% power or anything like that.

Hmm on a second look you are allowed to operate the engine leaned above 75% power for brief periods, so maybe it is that after all.

For the fuel flow part: imagine you are leaned for best economy, at 75% power. You change the mixture control to best power. This makes it so you are producing more power, so you throttle back to 75% power.
You now are producing the same amount of power as before, but with less air and more fuel. So the fuel flow is different.
My suspicion for the charts is that you should read the best economy charts as if you start out leaned for best power and lean for best economy without touching the throttle. That is, "75% power" means more like "the throttle position is set to where it would be for 75% power, if you were leaned for best power."
It makes sense if you read it this way- your cruise speed goes down a few knots when you lean since you are losing a bit of power by leaning.

Thanks, this makes sense as a possibility for achieving the lower stated airspeed, but as I've linked in another comment, there are some cruise performance charts that do contain "best economy mixture," which leaves me still suspecting my original confusion is due to a typo. But your framework still ties out, as I think it agrees with my suspicion that economy mixture yields a totally different (shifted) engine performance chart (pg. 98 in the original PDF). What do you think of that hypothesis?

I overlaid the figures from p. 101 and 102.  No great insight here, but I figured I would go ahead and share it.
Best economy in blue, best power in black.

I believe the confusion now arises from the use of the words "75% best power mixture" in the example on the middle of the chart on page 102 (the best economy chart).
I have no explanation for that, I tend to agree that the example should read 75% best economy mixture.

Thanks, nice chart. I managed to find another POH that does include "75% best economy mixture"...pg. 99 in the below. That said, pg. 100 is also a Best Economy Cruise Performance chart but is back to "75% best power mixture" -- but for a different subset of serial numbers. I wonder if this is just a repeated typo, or whether the leaning procedures/interpretations of what best economy actually is changed for these serial numbers. Unfortunately all POHs so far are completely silent on this issue.
https://www.montereynavyflyingclub.org/Other%20Docs/Piper-PA-28-161-Cherokee-Warrior-II-POH.pdf

Once a chart like this is approved for a POH, it is much easier to duplicate than it is to change.

I think there are a few things that you have confused.
First, Figure 5-15 on pdf p. 98 is not associated with any particular airspeed.  In fact, it is also independent of the propeller and the airplane in general.  It simply a chart describing the behavior of an engine at altitude.
At a given altitude and airspeed, a fixed pitch prop will absorb more power as RPM is increased.  (I think you were forgetting airspeed in the description above).
There may be some conditions under which the propeller fully stalls -- such that it stops delivering more thrust as the RPM is increased, but that is usually associated with such a large increase in power that it is not really achievable.  However, it is important to keep in mind that airplanes fly on thrust (or propulsive power), not shaft power.  The propeller efficiency is the difference.
Power required to fly at altitude at a given airspeed (and therefore the RPM) depends on the weight of the aircraft.  When you do your first solo, you will be surprised how sporty the aircraft feels without all that induced drag sitting in the other seat.

This misses the issue- that the two performance charts supposedly have everything equal except the mixture. Propeller efficiency is not going to be different just because the mixture control is different unless the power has changed. The weight is also the same for both charts.

@Chris-RegenerateResponse No, the first chart does not specify aircraft weight.  It also does not specify cruise conditions (thrust equal to drag).  The first chart is independent of the airplane (engine only).  The two charts have little in common with one another (not 'supposedly everything equal').

I'm referring to the two cruise charts on page 101 and 102, where the only difference is the mixture. I agree with what you say about the first chart on page 98.

@Chris-RegenerateResponse Sorry for the confusion re: p98.

Rob, thanks for the reply. I agree engine RPM is not always associated with specific airspeed: you could be in a challenging climb at full power for example, but at a low airspeed. My point was, if you are constantly trimming for level flight as you increase power (and for local ranges of power/altitude/etc), then the RPM is a monotonic function of % engine output; and, due to the level flight assumption, a monotonic function for airspeed. This is clearly a subset of configurations, but I was setting up a framework for interpreting the cruise charts (which are by definition for level flight).

@schopenhound This only holds for one weight -- but the chart is for 2300 lb.

If we were talking about true power then the resulting airspeed would be identical, with either a fixed or a constant speed prop. Assuming a fixed air density. (And prop governor setting)
But the operating manual is probably talking about a proxy for power like the absolute manifold pressure setting. The mixture ratio will change the true power output for a given manifold pressure setting.

Therefor the RPMs are not the same.

Thanks, makes sense. The POH is using "engine RPM" as the power output proxy. But I agree that for fixed inputs of throttle (not RPM!), the mixture changes the true power output.


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787 Dreamliner - What's the weird "thudding" noise I hear before take-off and landing
Frequent and a maybe-a-little-too-nervous flyer here.
Recently I've been taking the ORD-WAW course with LOT on the 787 Dreamliner and started noticing a sound that's been a little spooky for a person who's seen a little too many flight-crash explanation videos (I know, I'm trying to quit).
My next flight is in October, and before that I wanted to find any technical reason why I shouldn't worry.
The noise was captured on this youtube video. It's the "thudding" noise that cuts right before the video ends: LINK
This sound took place after landing but I believe I experienced it also before take off and it's accompanied but a rhythmic beating feeling from the bottom.
If there's anyone here who could elaborate on the supposed source of the noise it would be very helpful for me.
Additionally, if you guys could also elaborate on the high-pitched noise it would be even better because it's a sound I keep hearing before take-off and right before landing and it's scaring me every since the flight prior where after some technical-issues were fixed the high-pitch noise would be followed by this weird sound close to a high-pitched version of trying to start an engine, followed by a hissing-sound (which made me thing we're about to crash only...four dang times).
I understand this question might be a little vague, and if there's any details then I would love to elaborate.
Being and engineer I suppose I'm much more forgiving for strange noises when I somewhat aware what it could be.
Any help would be greatly appreciated!

Hopefully you don't get to the airport by car...

Learning what the different sounds are is good, but not the only way to manage nervousness about flying. Eventually you will hear other sounds that you can't identify and then the cycle repeats. You need to continually remind yourself how safe flying is. In the past ten years a total of five people have been killed in U.S. airline accidents out of 80 million airline flights. You might say I know that but I still feel nervous. It's like feeling hunger, it creates a primal nervousness, you have to keep reminding yourself that you are not in physical danger. Not saying it's always easy to do.

@StevePemberton Thanks for the feedback. Trying to dig into realizing what's making me so nervous though I found that what I fear is simply the sheer amount of moving parts a plane has that if one goes wrong everything falls apart. I know that there are people checking the planes but being an engineer in a different field myself I know how well people often check things...

@sophit I understand the statistics but then again if my engine fails, or the steering wheel stops working I can just stop the car and get out. In a plane its usually "nothing's wrong, till something is reaaaaly wrong"

Understand but still, travelling by car is some 60 times deadlier than flying! And the reason is simply that something going wrong in a car is much more probable than in an airplane: If your tire explodes while on the highway, you die; if your airplane loses a wing while flying, well it doesn't lose a wing in the first place

@aln447 - I am sure you have had a debate with someone who states facts out of context and refuses to acknowledge facts that don't fit the point they are trying to prove. Without realizing it you are doing this to yourself. Part of your brain is saying "airplanes fly at deadly altitudes, my life depends on many things going right. Cars are on the ground, if I have a problem I can stop the car and get out".  That part of your brain is refusing to acknowledge that 40,000 people per year die on U.S. highways. How well did the "I can just stop the car and get out" strategy work for them?

@aln447 - "I know that there are people checking the planes but being an engineer in a different field myself I know how well people often check things". Again this is focusing on only one facet. Statistics show that while imperfect they do an excellent job. Now consider driving, your life depends on the unknown random driver, in who knows what mental condition, who is guiding their 2-ton mass of steel within a few feet of your 2-ton mass of steel, at a combined speed of over 100 mph. Your life is in their hands. If you survive great, but now here comes the next car, and another, and another.

@StevePemberton I mean, you're 100% right, I fully understand that planes are much safer than cars. The problem I'm facing is the approach to the "one thing goes bad I'm dead" part of the equation, which does't happen in cars. With cars I feel safer hearing ie. a strange rumble because I know how to handle it. In turn in planes I know that the turbulences are ok and there's much handling in the plane for the turbulences so consequently I feel safer going through turbulence than through hearing strange sounds. I guess what would help is knowing how well planes are prepared for mech problems

I know it's dragging the topic out to almost psychoanalytical terms, and I apologize. I'm just trying perhaps finally acquire the logical mindset that "that weird sound is 99.9999% not going to make me meet Elvis"

Is Elvis dead???  Maybe something like this might help you

"The problem I'm facing is the approach to the "one thing goes bad I'm dead" part of the equation, which does't happen in cars." A) there are VERY few part of an aircraft where if "one thing goes bad you're dead", and B) there are plenty of parts of a car that will do the same (like a wheel coming off at 75MPH - oh, wait, that happened to me and didn't kill me either). Every commercial aircraft you'll ever fly in has at least 2 of every critical system, sometimes 3 or even 4, and they serve as backups to each other.

@aln447 - you are being selective in what you count as risk and this is giving you a false view of the risk of flying compared to driving. You seem to be looking for a way to continue to be selective but still reduce feelings of nervousness. This can be dangerous if it leads to being selective in the other direction about other activities, including driving, where we don't necessarily have to be paranoid, but which is where we really should be putting our attention. Like avoiding ever looking away from the road for more than a second (73 feet at 50 mph) or talking on the phone even handsfree.

@FreeMan That is a good point. I wasn't aware of the backup system. That's reassuring. I guess all of those examples I saw were before these systems were established. Then again we still make new mistakes, as was the case with 737-MAX where MCAS did not have a backup checking sensor even though the functionality was critical.

@aln447 backup hydraulic systems and computers have been common on commercial aircraft more or less since they were invented. The original 747-100 had backup hydraulic systems, as did the L-1011 and DC-10. (Quick examples from the 1960s off the top of my head - I'm sure they're far from the oldest with backup systems.)

Without watching the video, I can almost guarantee you the sounds you're hearing and movement you're feeling is flaps/slats moving (get a seat over wing and you'll see them moving) and if airborne then its undercarriage doors opening/closing and the gear locking into place. I assure you these sort of sounds are not out of the ordinary and almost certainly nothing to worry about.
Another sound you might hear/feel whilst still parked is the cargo bay doors closing and locking into place, again get the right seat and you'll hear it just after the last baggage cart moves away.

Thanks for the reply! What since the feeling was during taxi (although away from the gate) and after directly after landing then I believe it was the cargo doors.
What would you say about the high-pitched noise though? It's honestly the one I'm worried about more due to the "car-starting" sounds it made on my August flight.

@aln447There are so many actuators, and hydraulic/electronic systems on these jets that its hard bordering on impossible to know what every sound is.

@aln447: On Airbus you'll hear the sound of dogs barking in the cargo bays, it's for safety.

@Jamiec That's what I thought. Still hoped that since the high-pitched sound acompanies every start and landing procedures then maybe there would be some explanation to it. I'm slowly thinking if it's not the slats since the sound is usually long and happens at times when the plane would-probably-need-them. Still...if this sound produced the car-starting noises then means during the start and landing there was something wrong with them so...yikes?

@mins Yep. Heard of this. Unfortunately the sound is nothing like that.

Ok, the high pitch sound is 99% the flaps. I did some digging around this and found a video of someone experiencing the exact same car-start-up noises as I did:
https://youtu.be/R-XepgQKqhs?si=LZBPVJiylYUMj7DF&t=52
In this case I'm a little calmer knowing it's the flaps. Still wonder why suddenly they'd start to make that additional noise

Even better evident here: https://youtu.be/lbR80J8zmLg?si=kxK6gX38_YCx0Fxc&t=144
It's quite clearly the flaps since the moment the weird sound comes up, they start moving down. In this case it makes me wonder even more why I hadn't noticed it before since I've been flying 787 since 2011...

"far from the gate", @aln447, would absolutely NOT be cargo doors! Well, if it is, there should be alarms going off in the cockpit for an open door and they'll taxi to some stopping point where ground crew will come, pick up anything that fell out and stuff it back in the trunk, er, cargo hold, then latch & lock the door and triple check that it's closed correctly. Also, none of these sounds are specific to the 787 - they all make noises at varying volumes and you'll hear them on every flight if you're listening closely.

Marking the answer as the solution since it brought me the closes to the solution. Thank you all for the help!